open-ontologies

Overview

Open Ontologies is a comprehensive Rust MCP server that provides 43 tools for ontology engineering tasks. It features an in-memory Oxigraph triple store, native OWL2-DL tableaux reasoner, SHACL validation, SPARQL querying, and versioning capabilities. The server ships as a single binary with no JVM dependency, making it lightweight and easy to deploy. It also includes a desktop Studio application that visualizes ontologies with AI-powered building capabilities.

Try asking AI

After installing, here are 3 things you can ask your AI assistant:

• onto_validate

  Validates an RDF/OWL ontology for syntax and semantic correctness.

  Try:Validate this ontology for OWL2-DL complianceTry:Check if my RDF file has any syntax errors
• onto_load

  Loads an RDF/OWL ontology into the in-memory triple store.

  Try:Load the pizza ontology from fileTry:Import this RDF turtle data
• onto_stats

  Returns statistics about the loaded ontology including classes, properties, and individuals.

  Try:Show me ontology statisticsTry:How many classes are in the loaded ontology?
• onto_reason

  Performs OWL2-DL reasoning to infer additional triples and classifications.

  Try:Run reasoning to classify all individualsTry:What entities can be inferred as subclasses?
• onto_lint

  Analyzes the ontology for common design issues and best practices.

  Try:Check this ontology for design patternsTry:Are there any naming convention violations?
• onto_enforce

  Applies predefined design patterns and constraints to the ontology.

  Try:Enforce domain and range constraintsTry:Apply standard design patterns to this ontology
• onto_query

  Executes SPARQL queries against the ontology to extract specific information.

  Try:Find all vegetarian pizzasTry:Query for individuals with spiciness values
• onto_save

  Saves the current state of the ontology to a file in specified format.

  Try:Save this ontology as turtle formatTry:Export to RDF/XML file
• onto_version

  Creates a new version of the ontology with versioning information.

  Try:Version this ontology with current changesTry:Create a snapshot of the current state
• onto_diff

  Compares two versions of an ontology and highlights differences.

  Try:Show differences between version 1 and version 2Try:What changed in the latest ontology version?
• onto_align

  Aligns two ontologies by mapping similar concepts between them.

  Try:Align this pizza ontology with food ontologyTry:Find mappings between these two domain ontologies
• onto_build

  Builds a comprehensive ontology through a 13-step pipeline with reasoning and validation.

  Try:Build a comprehensive cat ontologyTry:Create an ontology following the Manchester tutorial

Comparable tools

Installation

# macOS (Apple Silicon)
curl -LO https://github.com/fabio-rovai/open-ontologies/releases/latest/download/open-ontologies-aarch64-apple-darwin
chmod +x open-ontologies-aarch64-apple-darwin && mv open-ontologies-aarch64-apple-darwin /usr/local/bin/open-ontologies

# Linux (x86_64)
curl -LO https://github.com/fabio-rovai/open-ontologies/releases/latest/download/open-ontologies-x86_64-unknown-linux-gnu
chmod +x open-ontologies-x86_64-unknown-linux-gnu && mv open-ontologies-x86_64-unknown-linux-gnu /usr/local/bin/open-ontologies

{
  "mcpServers": {
    "open-ontologies": {
      "command": "/path/to/open-ontologies",
      "args": ["serve"]
    }
  }
}

On Hacker News

Recent discussion from the developer community.

• MCP tools for AI-native ontology engineering (Rust and Oxigraph)▲ 3💬 1
  Story by fabio_rovai · 2026-03-12

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